The present invention refers to a threaded nut or device of rapid release which allows connecting two different components through a screw or bolt or device and the threaded nut. The objective of the invention is to remove the threaded nut or device from a threaded bolt or device as faster as possible without conducting the typical action of unscrewing which is the current practice.
The present invention relates to a fast extraction threaded nut or device which allows removal of the threaded nut or device in a prompt and efficient manner for applications in the mining industry, in particular to attach lining casing of mills. More specifically, this invention refers to a medium of mechanic articulation similar to a typical threaded nut or device where certain notches have been made which weaken the threaded nut or device only when the nut is removed and the articulation allows the nut to be completely operational when in use. The removal process of the threaded nut or device is accordingly faster and the process might take 5 seconds depending on the tool used to notch the threaded nut or like. It should be noted that the benefits provided by a rapid removal action consists of increasing the availability of the equipment. At present a SAG mill with a 40′ diameter (12192 mm) and 20′ length has a 90% availability and more, it processes approximately 100,000 TPD (tons per day), which provides approximately US$ 100,000 per hour of production. Replacement of lining includes an average amount of 30 hours in activities, and 10 of these 30 hours are spent to remove the bolts or threaded nuts. It would be then beneficial to reduce such time by using a threaded nut or device of rapid removal as it would increase availability in at least 5 hours with a subsequent increase in production amounting to approximately US $500,000, when linings are changed once or twice during the year.
Normal operation of a threaded nut (when connecting two components that are intended to maintain connected) generates in a functional way a stress field of compressive nature in virtually all the threaded nut or device. Such condition of compression stress prevents stress concentrators from presenting a risk condition which can destroy the threaded nut or device as it is not possible to propagate the extension of a crack inside a field of compression stress. The aforementioned has been tested both at experimental level by conducting a series of experiments which considered the geometric variables of the notching and material variations (different alloys and shape of the threaded nut or device) and also by simulations conducted based on the method of finite elements. The dimensions of the notching are the main characteristics which make the threaded nut or device rapidly removable. Measurements for depth (see magnitude B in FIG. 2) and thickness (see magnitude A in FIG. 2), angles of notching (see magnitude C in FIG. 2) which when placed on an antagonistic position and are subject under the action of wedges allow cracking of threaded nut or device of rapid removal by separating such nut into two or more parts as shown in FIGS. 4 and 5.
In order to improve the performance of the threaded nut or device several different alloys and geometries have been tested as well as other accessories have been added allowing the threaded nut or device to be affixed in a safe position when in operation. In consequence, this system for connection has the characteristic of not becoming loose or breaking when in operation and provides a rapid separation during the removal process thus becoming an innovative manner of decreasing the time to replace linings for any given mill.
In the art, patent GB 767882 discloses a threaded nut or device jointly shaped with a washer. In one side of the nut, a pair of radial walls extends toward the edge of the washer. Both walls provide a rectangular radial slot opened in the inner portion of the threaded nut or device, that is, both the nut or device and the washer are divided by that slot. The washer has a line of weakness in the opposite side of the slot. This threaded nut or device is intended for use in bathroom and kitchen devices and equipment as when such devices are rusted rendering very difficult removal of the threaded nut or device. Then through a radial leveraging in the radial slot the threaded nut or device is broken in the line of weakness thus repairs can be made in such equipment without any problems. In this case, the threaded nut or device and the washer are jointly conformed and also present one side which is completely opened with the slot in the radial direction while on the other side they have a line of weakness in the axial direction. When tightening the threaded nut or device during assembly it tends to open as a result from the slot, thus ceasing in its objective of providing a point of union to the parts that are affixed. This threaded nut or device is designed to endure lesser tightening and to be used in equipment for kitchen and bathrooms and it can not be applied to mobile devices subject to greater loads and stress during their operation and use.
U.S. Pat. No. 5,139,381, describes a system for rapid push-on mounting of a piece which is equivalent to a slide fit nut to be placed on a threaded bolt or the like whereas the device comprises three pieces wherein two of them have external hexagonal shape and one of these two pieces has a cylindrical array bore where the third piece is inserted, and wherein such third piece is divided into four threaded parts matching the threaded bolt. The system is rapidly disengaged when rotating the upper part of the piece connecting the portions of the cylindrical piece which are radially disengaged, thus detaching from the threaded bolt and thus it is not necessary to rotate the element using a wrench as to remove the slide fit nut wherein it can be extracted by pulling upward without any difficulty.
U.S. Pat. No. 6,406,240 B, describes a system similar to the previous one but in this case the cylindrical bore threaded coupling the bolt is divided in three cams that move in radial direction disengaging from the thread when the upper portion is axially moved through rotation applied to the hexagonal head and is different to the previous patent as the second cam of the threaded nut does not have an external hexagonal head.
It should be noted that all inventions related to rapid extraction have in common the use of more than three pieces as to achieve the objective. In this case in the present invention, and which is the novelty element, is that there is only one element acting with the bolt. This is a really differentiating factor compared to the other systems proposed which makes possible to reduce manufacturing costs of the new threaded bolt and which takes advantage of the existence of the threaded nut commercially available, which these new machined elements would need to be added to.